If the printer is feeding paper through but there is no text visible on the print out. To resolve this issue we need to know what type of printer you are using. There are two types of printers:
Thermal Printer - uses thermal paper
Dot Matrix Printer - uses non thermal paper and an ink ribbon
If a Thermal Printer is not printing text:
Check that thermal paper is being used.
Check that the paper roll has been inserted in the correct way.
If a Dot Matrix Printer is not printing text:
Check that non thermal paper is being used.
Check that there is an ink ribbon and it's correctly seated.
Try a new ink ribbon.